1. Field of the Invention
The present invention relates generally to the field of medical implantation devices and, more particularly, to an improved fiberoptic-guided interstitial seed manual applicator and seed cartridge.
2. Description of the Related Art
Afterloading brachytherapy has been in use since 1960 when it was pioneered in the United States by Ulrich Henschke. In this medical procedure, malignant tumors and the like are treated by surgically implanting radioactive sources (xe2x80x9cseedsxe2x80x9d) in or about the malignant tumor in order to irradiate the malignancy. The term xe2x80x9cseedxe2x80x9d as used herein is intended to broadly mean an object or body to be implanted within a patient, including, but not limited to radioactive seeds used in brachytherapy procedures.
A variety of different radioactive materials have been used as seeds. For instance, Basil Hilaris was the first to use Iodine-125 for permanent implantation in a tumor. Since then, use of Iodine-125 has persisted, serving as the seeds used in the vast majority of interstitial brachytherapy implants for a host of tissues and organs. More recently, Palladium-103 has been approved for use as an implantable radionuclide and applications using Palladium-103 continue to be explored. Other radioactive materials that have also been used include Radon-222, Gold-198 and Iridium-192.
Precise location and spacing of the implanted seeds is of particular importance in the treatment of such malignant tumors and the like. Poor location or distribution of seeds can result in undesirable concentrations of seeds leading to either an overdosage or underdosage of radiation. As such conventional interstitial seed implantation is frequently performed through an open surgical incision in the patient. In one conventional technique, hollow needles are inserted into the tumor and the seeds are thereafter placed in the needles while the needles are being retracted to implant or deposit the seeds in the tumor. Popular instruments commonly used today for surgically implanting seeds in or about the tumor include the Henschke, Fletcher-Suit, and Mick applicators, Royal Marsden gold grain gun, and stainless steel needles/hairpins. With few exceptions, however, the basic concept and design behind most of these seed implantation systems have changed little over the years.
In contrast, the last two decades have witnessed remarkable advances in surgical, imaging, and anesthetic practices, as well as new developments in permanent radionuclide source availability. Despite the fact that many surgical procedures are currently accomplished using conventional endoscopes or laparoscopes with minimal or limited incisions into chest, abdominal or pelvic wall tissue, conventional implantation systems have generally failed to combine such a technique with brachytherapy implantation due to a dearth in brachytherapy technology.
While many problems associated with interstitial seed implantation have been addressed by the above-mentioned conventional implantation instruments, there remains a tremendous need to develop an interstitial seed manual applicator that utilizes fiberoptics and is capable of precise implantation of seeds using minimal or limited incisions into chest, abdominal, or pelvic wall tissue of a patient.
In addition, seed handling in connection with brachytherapy has not changed since the inception of this therapeutic approach thirty years age. Seeds may be ordered from a distributor and typically arrive loose in a protective lead-lined pig. Seed strength and number of seeds are generally communicated on the appropriate paperwork accompanying the seeds. Following delivery of the seeds, however, all further seed handling duties are typically accomplished manually by the radiation oncologist or related technical staff. These duties include seed counting; loading seeds into the appropriate cartridge, needle, or magazine; sterilizing the seeds in their receptacle for use in the operating suite; keeping a running tally of the number of dispensed seeds in the operating room with paper and pencil; surveying of the operating suite following the procedure in order to track possible loose or stray seeds; and frequent switching of empty seed cartridges, needles, and magazine due to limited seed capacity.
Not only is this current seed handling procedure labor-intensive, but it invariably leads to radiation exposure of the personnel involved. In the best of circumstances, seeds can jam or dislodge from their receptacle and become temporarily or permanently misplaced. Sterilization of seeds intraoperatively wastes precious time and maintaining an accurate seed tally can be confusing. Accordingly, there is a tremendous need to develop a device that simplifies seed handling in connection with brachytherapy and minimizes the above-mentioned problems associated with current techniques.
By the use of the present invention, it is no longer necessary to limit brachytherapy applications or other implantation procedures to instances involving large, open surgical wounds or incisions. Rather, seed implantation may be achieved with fiberoptic or other optical assistance through a small incision associated most commonly with minimally-invasive surgery, as well as with the traditional large, open surgical incision. In addition, the fiberoptic or other optical assistance provided in accordance with the present invention facilitates accurate seed implantation into the target tissue using direct visualization of the seed passing into the tissue. Such an advance in seed implantation technology as a result of the present invention will broaden the applicability of interstitial implantation to include those patients who undergo fiberoptic-guided tumor biopsy and ordinarily would be sent for external beam radiotherapy thereafter; patients who medically cannot tolerate a large incisional wound; patients who are poor operative candidates based on technical considerations, such as those who have been previously irradiated with external beam therapy and whose tissues would heal poorly with additionally radical surgery; patients with recurrences following either surgery or radiation therapy; or patients in whom minimally-invasive interstitial implantation is deemed advantageous. The unique features of the implantation technique and manual applicator according to the present invention, including its fiberoptic guidance, minimally-invasive surgical requirement, automatic firing mechanism, gravity-independent posture, and integral dispenses/remaining seed visual indicator all serve to enhance the attractiveness and utility of interstitial brachytherapy, in general, and of this novel system in particular.
The foregoing and other objects and advantages are achieved in accordance with the present invention through the provision of a fiberoptic-guided interstitial seed manual applicator (FOGISMA) or implantation device. According to the present invention, a method and system is provided for interstitial implantation into or around neoplasms of tumoricidal or tumoristatic doses of radiation carried by radioactive seeds whose placement is guided via an intrinsic fiberoptic or optical component, potentially, but not necessarily, enhanced by laparoscopic, thoracoscopic, bronchoscopic, cyctoscopic, or other types of assisted surveillance including direct vision. The FOGISMA device according to the present invention may require minimally invasive surgery in order to introduce the applicator through a smallincision into the target tissue, rather than the wide open incision required by previous techniques.
With proper mounting, the FOGISMA device according to the present invention may also be used for percutaneous seed implantation, such as through the transperineal route for implanting the prostate gland. The same automatic firing mechanism and precision needle positioning as with the minimally invasive technique would apply, with the advantage of knowing the exact location of the needle tip by fiber optic guidance. The radioactive seeds are introduced one at a time from a shielded seed magazine down the a barrel of the applicator into the target tissue using a gravity-independent automatic firing mechanism instead of the conventional manual plunger, and the introducing needle is automatically withdrawn the desired amount by the precision FOGISMA device. Seeds may be placed sequentially along a given needle track and/or in separate needle tracks, while maintaining an integral visual numerical indication of all dispensed/remaining seeds.
In accordance with the present invention, an implantation device is provided for implanting seeds within or adjacent to a target area, such as a tumor, located within a patient. The implantation device comprises an implantation needle having a bore extending longitudinally therethrough from a proximal end to a distal end of the needle. The needle bore is adapted to permit at least one seed to pass therethrough into the target area. An elongated plunger extends longitudinally through the implantation device in aligned relation to the needle bore and is selectively movable in the longitudinal direction relative the needle from a retracted position spaced apart from the needle to an extended position wherein the plunger is advanced through the needle bore to eject at least one of the seeds through the bore, out of the distal end of needle and into the target area. An optical device is carried by and operatively connected to the plunger to provide visual assistance to an operator of the implantation device to guide and verify implantation of the ejected seed into the target area.
The FOGISMA implantation device of the present invention may also comprise: (1) a multi-seed cartridge, either pre-packaged or loaded ad hoc, which is inserted into the proximal end of the device; (2) an operational/controlling proximal end with a grip that allows the user, manually or with robotic assistance, to adjust and guide each motion related to seed placement; (3) a rotating loading barrel in the mid portion of the device that assures precise transfer of each individual seed from the loading chamber into the firing chamber; (4) an introducer needle attached to the distal portion of the device that is effectively exposed from a protective sheath, enabling the needle to be driven into or around the tumor, thus providing a channel for seed insertion; (5) an outer sheath that functions as a protective housing for the introducer needle in its resting position and is adjustable to appropriate shorter lengths as required to permit a given length of the introducer needle to protrude for desired tissue penetration. Upon firing a radioactive seed into tissue, the subsequent seed in the seed cartridge will automatically shift into firing position, permitting easy and rapid firing of any number of seeds deemed appropriate. Additional seed cartridges may be required and can be exchanged for exhausted cartridges as necessary.
The present invention further addresses the glaring shortcomings of conventional seed handling in a way that will facilitate the use of the therapeutic modality by both seasoned practitioners and those who have been reluctant to attempt it in the past because of it inherent disadvantages. A Brachytherapy Interstitial Seed Cartridge (BISC) is provided in accordance with the present invention to hold a plurality of seeds for use with an implantation device of the type having a seed alignment channel, a hollow needle and a moveable plunger that causes seeds within the device to pass through the hollow needle and be implanted within or adjacent to a target area, such as a tumor, located within a patient. The seed cartridge comprises an elongated cylindrically-shaped core member having a seed conduit extending longitudinally therethrough, the seed conduit being adapted to retain the plurality of seeds in end-to-end aligned relation prior to feeding the seeds into the seed alignment channel of the implantation device. Locking means are provided to releasably connect the core member to the implantation device so that the seed conduit is in aligned relation to and communication with the seed alignment channel of the implantation device. An elongated seed advancement push rod is slidably received within the seed conduit to move longitudinally within the seed conduit to cause the seeds contained within the seed conduit to advance into the seed alignment channel of the implantation device from the seed cartridge.
The BISC seed cartridge may be a preloaded, self-contained seed cartridge for brachytherapy or other operators and is adaptable for a host of implant applicators. This delivery system comprises of a protective outer casing that stores a pre-sterilized cartridge containing the seeds. The easy-lock and unloading of the seed cartridge facilitates implantation by: (1) precluding exposure to staff before the implant; (2) ensuring a verified seed count; (3) eliminating the potential for seed spills or inadvertent loss due to seed manipulation in the brachyterapy hot room or operating suite; (4) efficient use of physician and operating room time by eliminating the need for autoclaving of the seeds/cartridge before use in the operating suite; (5) allowing rapid deposition of seeds that are preloaded with many more seeds per cartridge than the standard number allowed by today""seed magazines; and (6) limiting the potential for seed jamming or other misapplication through the smooth mechanical action of the seed cartridge.
The foregoing specific objects and advantages of the invention are illustrative of those that can be achieved by the present invention and are not intended to be exhaustive or limiting of the possible advantages which can be realized. Thus, these and other objects and advantages of this invention will be apparent form the description herein or can be learned from practicing this invention, both as embodied herein or as modified in view of any variations which may be apparent to those skilled in the art. Accordingly, the present invention resides in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.